The present invention relates to a tool for gripping remotely located articles and more particularly to a gripping tool having spaced parallel jaw members which are manually actuated.
A search of the prior art failed to uncover any prior art references which disclose the gripping tool of the present invention. A number of patents were uncovered which disclose various article gripping tools. The following is a listing of the patents uncovered during the aforementioned search:
______________________________________ U.S. Pat. No. Patentee Issue Year ______________________________________ 1,455,613 Heppenstall 1923 2,493,108 Casey 1950 2,916,323 Van Berkum 1959 3,312,496 Boutelle et al 1967 3,937,512 Baughman 1976 4,005,897 Smith 1977 4,039,216 Soos 1977 4,669,769 Polder 1987 ______________________________________
Gripping tools such as those in accordance with the present invention find their primary use in the nuclear reactor industry. These tools as designed are intended, among other things, for handling radioactive materials under water. High level radioactive materials are stored and handled in clear water fuel pools in the nuclear industry. Such pools are very deep, some, for example, being as deep as 120 feet. The water provides shielding for the environment and the personnel handling the nuclear material. At the same time, the nuclear materials are cooled and stabilized.
At times it is necessary to be able to reach into the nuclear reactor, using a gripping tool, to retrieve unwanted or dropped items from the reactors. Some reactor vessels are 120 feet deep from the work platforms. Items to be handled vary in size from small flakes to very heavy objects such as nuts and wrenches. In one incident which resulted in a three day delay of a reactor start-up, a cold chisel which was being used some distance from an open fuel position in a reactor vessel, inadvertently dropped into the reactor opening. The cost of retrieving the chisel was estimated at over $400,000.00.
Prior art gripping tools are known in which the jaw faces do not maintain a parallel relationship during the gripping operation, such as U.S. Pat. No. 3,219,376 of the present inventor and U.S. Pat. No. 1,455,613 to Heppenstall. For example, in the tool of Heppenstall, the jaws are spring-loaded and any parallelism of the jaws is the result of the shape of the object being grasped when the jaws are closed. A further prior art device is disclosed in U.S. Pat. No. 3,312,496 to Boutelle et al, which attempts to maintain the parallelism between the two jaw faces as the jaw members are moved between the open and closed positions. However, the device of Boutelle et al employs a complicated mechanism, which is not suitable for use in the nuclear industry. In the nuclear industry simplicity of design is an important factor, since in the handling of nuclear or hazardous products all potential aspects of safe operations must be considered and the tools must be designed to contain the least possible points of failure with a bare minimum of parts which, in use, could possibly fall off or otherwise be dislodged. Furthermore, in these devices the closure method should offer a feature of instant opening of the jaws should a member fail due to breakage or failure. Thus, the gripping tools for the aforedescribed application in the nuclear industry should be as fail-safe as possible.
While the current use contemplated for the gripping tool of the invention is primarily in the nuclear field, a much broader application of the tool is, of course, possible. For example, the gripper in accordance with the present invention could be used on robotic equipment. Forest products could be handled by the gripping tool of the invention, if the tool were made on a much larger scale. Hydraulic and air closing operation of the tool is also possible. Grippers for unmanned submarines and outer space uses are also possible. The device could also be useful for handling high temperature objects, such as in the blacksmithing art or for laboratory use.